StringPowerBlock.pdf is probably the most interesting one. This is a block of one 250nm communicator chip and seven 28nm chips. Here you can see how the individual blocks are interconnected (differential pairs), hashing chip connections and how the StringPower design that BitFury pioneered with our first 55nm chip works.
Is the chip named Bitfury_POWER in StringPowerBlock.pdf the one that is on the boards (on 1block_short.jpg BF250K3N48), because the pin-out is different - 40 vs 56 pins
If it is the same "250nm communicator chip" but different revisions or the bigger one is just for more chips, which of them is the latest revision and for how many chips?